It is known in the art that artwork or relief images can be formed by photocuring photosensitive polymeric material. This process is particularly useful in the formation of hand stamping devices and other printing devices which require a wide variety of images to be produced. Image plates for hand stamping devices are normally produced in a sheet containing multiple individual image plates due to the typically small size of the image plates or stamps being produced. Typically, the photocuring process involves laying down a negative on a photopolymer exposing unit such as a light box and pouring a liquid photopolymer over the negative to form a photopolymer layer to be cured. A substrate which includes an adhesive layer on the inner surface is then placed on top of the photopolymer. The photopolymer is exposed to light transmitted through the negative to create the desired relief image or group of letters on the stamp. The adhesive layer on the inner surface of the substrate creates a strong adhesive bond between the substrate backing material and the photopolymer used to create the image. This backing material rigidifies each of the individual stamps and provides a carrier for the photocured material. After the polymer material is photocured, the entire unit is washed and final cured. Thereafter, individual stamps or image plates are cut from the continuous carrier sheet.
As an example, U.S. Pat. No. 3,848,998 discloses a process and apparatus for producing a photopolymer plate incorporating relief images thereon which includes an apparatus for developing the photopolymer plate. An image-bearing transparency is placed on a rigid glass plate capable of transmitting actinic radiation. A sheet of protective film which is also capable of transmitting actinic radiation is placed over the image bearing transparency. A layer of liquid photosensitive material is then applied to the upper surface of the sheet of protective film material and a sheet of backing material is laminated onto the upper surface of the photosensitive layer to form an assembly. The photosensitive layer is then exposed to photocuring light through the transparent portions of the image bearing transparency. The sheet of protective film material is then removed from the lower surface of the exposed photosensitive layer to reveal the photocured photopolymer layer and the sheet of laminated backing material. This assembly is then washed in order to remove the unhardened, nonexposed, photosensitive material. The relief image remains on the sheet of backing material as an integral assembly. In order to obtain individual image plates it is necessary to cut them from the integral assembly. The relief image formed on the sheet of backing material may then be used on a variety of printing equipment.
U.S. Pat. No. 4,087,182 is a modified version of the above-identified patent. This reference utilizes a second or auxiliary light source located above the backing material. A dotted image-bearing sheet may be used to cover the auxiliary light source. The dots are preferably sized such that 30 to 150 lines of dots per inch are formed on the sheet. The dots increase transmittance of radiation to the sheet and can form projections or studs between the larger projections which are exposed to light from the bottom light source in order to prevent unwanted compression of the studs and smearing.
The related art requires the substrate as backing material to provide sufficient strength and rigidity to the image-bearing relief plate. The related art also requires sheets containing multiple relief images or individual stamps to be cut from the sheet. The cutting of individual stamps can be particularly problematic because after cutting the stamps from the sheet there is no means to maintain them in a pre-defined orientation.